(a) Field of the Invention
The present invention relates to a hybrid vehicle. More particularly, the present invention relates to a system and a method for controlling motors of a hybrid vehicle that controls the torque of each motor efficiently and stably by distributing total demand torque to a plurality of motors efficiently, when the plurality of motors provided in the hybrid vehicle operates under a predetermined condition.
(b) Description of the Related Art
A hybrid vehicle uses one or both of an engine such as a gasoline engine or a diesel engine and an electric motor operated by a battery power source.
The hybrid vehicle achieves various drive modes so as to improve fuel economy or power performance by using at least two motors and a coupling means such as a clutch.
For example, the hybrid vehicle achieves an engine mode at which only the engine is operated, an EV mode at which the engine is stopped and only the motor is operated because engine efficiency is low (drive with a low speed), and a HEV mode torque of the motor assists torque of the engine (high load region).
Drive region of the motor is divided into a region where torque is smaller than continuous rated torque and another region where the torque is higher than or equal to the continuous rated torque and is smaller than or equal to a maximum torque. Each drive region of the motor is set considering heat generation of the motor when operating and the capacity of a cooling system.
If the motor is operated at the region where the torque is smaller than the continuous rated torque, cooling capacity exceeds the heat generation and the motor can operate continuously without an increase in motor temperature. On the contrary, if the motor is operated at the other region where the torque is larger than or equal to the continuous rated torque, the heat generation exceeds the cooling capacity and the motor temperature rises. Therefore, the motor cannot operate continuously.
In addition, efficiency characteristics of the motor changes according to a drive point decided based on the torque and the rotation speed thereof.